What petrol.

Difficult to avoid ethanol-containing fuels within the EU.  Legislation sez at least 5% needs to be included, so no great difference if 90, 95 or 100/102 octane is used.  E10 super(95) contains at least 10%.

Well-seasoned engines with valve seats that have been clobbered nice and wide over thousands of km won't suffer much through the use of un-leaded.  Usually not much compression left to justify the use of higher than 95 octane either... :D  The seats work-harden over time, and with the extra (detrimental, from a technical viewpoint) width, the specific pressure of the valve on the seat is greatly reduced, as is sealing and engine efficiency.

Overhauled engines with seats freshly cut in the soft cast iron skull will surely suffer quickly with un-leaded, especially if the seats have been cut narrower to promote sealing, flow and efficiency.  Triple heads where this is still possible are few and far between nowadays, still possible on many 750s though.  Only way around this is to fit seat inserts suitable for un-leaded fuels.

piet
 
Grant said:
I'll add that I was sitting at around 70 to 80mph for each trip, so not high revs.
Average speed including fuel stops was 100kph which is around 60mph.
Leaded fuel used to build up a coating on the valve seats and acted as a cushion of sorts. This memory would have been wiped/burned off after 18 hours (effectively) non-stop riding. Only around 5 mins per fuel stop.
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"Load and speed

Comment: this chart just depicts how the wear rate can be distributed all over the load/speed map. The peak around high speed/50 % load is predominantly determined by the point(s) where closed loop is abandoned and enrichment becomes effective."

If you look at the graph, 50% load and 4000 to 5000 revs will do the trick.

 
Have been pondering this very question (but don't feel like reading an inconclusive article full of graphs and stats  8) 8) 8)).

My SF head had new seats fitted years ago, before leaded was phased out, but I'm assuming they are harder than the cast skull seats of the std head. Having last run when 'lead replacement' was available, I've never run it on unleaded (yes, it's been a while!!!) I don't know what will happen, but I do intend running it on 95 or 98 and not using additives. The pinging issue is not associated in any way with the valve seat recession issue (octane vs seat cushioning - the anti-knock properties of lead have been overcome with higher octane unleaded ratings); the latter does seem enigmatic! (but if I were Grant I would probably say problematic ... AND emphatic  :D).

The stock SF1 I've been riding I run on 95 or 98 with no additive, std seats. We shall see - no closing tappet clearances so far with maybe 1500km on freshly cut seats ... here's hoping.

maybe we could get Sf owners and triple owners to respond, who uses additives for valve cushioning and who doesn't, who's had probs and who hasn't ... there are enough of us to establish some 'survey facts'.
 
Not an SF I know, but I took the advice from the "inconclusive article full of graphs and stats" and have run the 81 Le Mans III on straight unleaded for the last 3 years. 98 when available and 95 (and even 91) when not. No valve seat recession at all.

His conversion method (same as mine) :-

"The T4 i am going to buy, once was converted to unleaded fuel, even before the leaded fuel was phased out, by the following simple procedure:
don't touch the engine
stop filling leaded fuel
start filling unleaded fuel 95 RON
operate the bike as usual"
 
I am certainly with grant on this one.

My first valve seat failure was also a long run (and to a Dutch rally as well!) this was to Appelscha in around 1999/200/2001 I cant recall exactly) but for sure leaded fuel was getting scarce, I was buying it whenever I could but during the trip, I was forced to fill (maybe) three times with unleaded fuel. TOG was being run very hard, this was before her cosmetic makeover, and I was heavily loaded with camping gear for two, plus my youngest son (David) as pillion, motorway speeds were a constant 150 KPH with fuel stops every 180 or so k's depending on availability, it has to be said that no amount of very hard wide throttle openings can help you with fuel consumption like that, the average speed will always be disappointingly low. But thrash on I did in those days, we didn't make it back to UK.TOG failed, and we got recovered home (in those days they just collected you, dropped you at Calais and arranged another truck for Dover, none of this separating rider and bike stuff)

back at home the investigations  found that the valve seats had all closed, the exhausts on two cylinders were Zero or negative (not easy to tell) and the main failure was the other exhaust valve head had parted company with the stem and chewed the piston crown right out and the top of the rod for good measure.

This was my first big failure, I have loads ever since, I have heads repaired by many well known sources and never been satisfied (Mr Nairn, nor Mr Todd have never done one for me) I got going again properly by buying a new unused (still in makers packaging) cylinder head from Toddy, it is RGS spec, all that took me about 12 years, I wish I had bought three brand new heads when I could have
a) obtained them easily and b) afforded the cost

The lack of reliability and the huge fuel consumption is what has done it for me
These days I ride a very old pan European Honda, ultra reliable and 470/500 k's between fill ups and double the economy of TOG,
and as the owner/rider of possibly the fasted jota in the UK will testify if pressed, it is as quick as his bike, such a shame mine handles like a barge and stops like a swan landing on ice.

CLEM
 
Hello there Clem, kind of you to big up my Jota! It is sweet...interesting because as you know, it too has a new head...an RGS one taken off the showroom engine at Slaters by none other than you and Richard Slater!! It did have to go to Keith after I bent some valves in what we think was a missed gear over revving incident. By the way, on something of a thread high jack, I took the BMW to the Edenbridge race suspension place you recommended, and had bloody pricey  Wilburs fitted and set up front and back, just before 2 up trip to Holland.incredibly stable bike now, rides like on rails....like the Jota which also wears Wilburs.
 
I recall, many moons ago, pouring a about 1/2 a gallon of 100 Proof moonshine into a Mini and climbed a ski hill on new years eve. We drank the rest of it mixed with grape juice - I think we labeled it "Purple Jesus".

By the time we got to the top, there where a few Cop Cruisers at the bottom with a mega-phone and search lights trying to talk us down but we replied "You come up". They left knowing it was a useless attempt to apprehend us for reasons unknown - LOL

Needless to say we became to talk of town and every one could not stop laughing while we recuperated. I remember my Dad with a very stern face in the morning of New Year day at breakfast when I stumbled in and he burst out laughing. My mother did know what to make of it while I crawled up to bed.

I know I lost most my brain cells that night.

Gotta say, there's nothing like climbing Ski-Hill with a Mini and a gallon of St Mic Pierre Moonshine on New Years Eve.

 
Well, that's cleared up one mystery  :D

(all in good fun Ron)
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Good story Huh! But it's the truth - The things we did, with enough Anti-Freeze, on New Years Eve when we were young ;o)

That poor old Mini got past around and a blast to drive. All you had to do was mat the gas pedal and keep shifting. You didn't care if you where going straight, sideways or spinning backwards.

I got her with the rear end knocked out, for free. Apparently he hit a stock pile of Railway Rails hidden under the snow. He claimed he didn't see them, wonder why, and drove it home with back end of the car on a toboggan - LOL

I scrummage a couple of tie plates and hydro pole cable with a few clamps to remounted the rear end and she was back in action ;o)

I drove her a winter. The only problem I had is that I kept loosing her as she had a sleeping habit under snow banks. I would look for the biggest snow bank and sure enough with a little digging I would find her buried and frozen. All I had to do was clean the snow from around her SU and access the drivers door. Pour a quart of hot water over the SU spray a little of ether. She would wake up and pull away with the snow bank.

That thing was awesome in the snow and off road and if you weren't drunk enough you could always drink the Alcohol from the Suspension bags. She sure loved Moonshine for petrol.

She was a devoted alcoholic and I still tip a glass in her memory - LOL
-------------------------

Of my 3 friends and I whom pulled that stunt off we were too sick laugh for the next week.

 
What a great tale mate. Keep ?m comin`!! You should put it all down in a book.
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Thank you:

Tell that to my English Teacher, whom I revere. She constantly failed me in English because I refused to respond to Shakespeare or boring books like: Dickson's Great Expectations. I read a lot through Encyclopedias, Fantasy, Si-Fi  (Asmonoff), Lord of the Rings, the Matrix, Lord Dunsany , Carlos Castaneda ..etc in the 60's, Columbia Desk, Popular Science, Mechanics and Atlases but she DID teach me how to write all though our views where completely opposite - She had the power to grade.

As a matter of fact she never signed my Grade 13 High School Graduation Certificate or would admit that I was viable English Student.

No matter how much that woman nagged me, I hold her in respect and love her. I just didn't agree with the Canadian Academic English course she was teaching at the time.

I spent more time in the back room argumentative with her then any other English student and neither of us would back down. In the long run I had too adjust to get outta Hi-School as my way ward path was corrective or prioritize to suffice the STD Agenda in her opinion ;o)

I dare anyone to read Dickson's Great Expectations without falling a sleep from 1500 pages of repetitive classic stanza style paragraphs of board-um of a great story that could have been written in under 200 pages which brings us back to the fuel that keeps the fire burning.

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Whenever I'm fortunate to come across one of the perpetrators of the crime they always blame me for suggesting such an outrageous stunt on a New Years Eve and we can laugh about taking a Mini up a mountain on Moonshine. I know for sure it wasn't the act as it was memorable but the 3 day  hangover was a beggar.

As a matter of fact the locals, whom I do not know today, name that Ski Hill "Moonshine"..

---------------------

Seems to me I was always surrounded by women in English class. When students had their (Her) copy of Great Expectations open I was reading Dunsany's King of Elfland's Daughter. Then I would get kick on my chair and slipped a taboo copy of the book to girl behind me.

You don't want to hear the story on how them Girls in English Class tortured me in Hi-School. Especially when they where on their period. Jocks envied me - Hah! It was a nightmare. Not that I didn't love every one of them. Out of a class of 40 there was 4 guy's Vs 36 girls in Academic English.?

OK you asked for it.  Here goes:

All you need is 4 girls on their period all around you. That is in front, beside and behind you. Slipping and sliding on maxi's. The odor is over powering. You sink into your seat and the last thing you need is a hard on.

So I get up and rush out of the class with one straight leg and Miss Fliss, our English Teacher, screaming "How dare you leave my class Ron. Report to the Principle's Office". All the girls are grinning and chuckling when all I want to do is find the nearest washroom were I can cool it with cold water and take a few deep breaths.

I say it was a conspiracy.

Other then that story is fuel for thought, or not, it is a torturous tale of destruction and Miss Fliss never admitted to not appreciating my stories ;o)
 
who said I was bigging you up Nicko!
without doubt your Jota is a quick one, and I have not ridden it I don't think, only followed it closely, you might have been right all along though, just not saying.

the quickest 1200 that I have ridden, (and it was deffo the scruffiest) now that's another story
CLEM
 
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